Perforated sheet metal



uy 29 i924., L5273 G. A. @BERG PERFORATED SHEET METAL Filed NOV. l5 1922 Patented July 29k, 1924.

UNITED STATES PATENT OFFICE.

GUNNABD A.. OBERG, OF JAMESTOWN, NEW YORK, ASSIGNOR TO BLACKSTONE MANU- FACTURING COMPANY, OF JAMESTOWN, NEW YORK, A CORPORATION 0F NEW YORK.

PERFORATED SHEET METAL.

Application led November 15, 1922. Serial No. 601,198.-

To all lwhom t may Be it known that I, GUNNARD A. OBERG, a citizen of the United States, residing at Jamestown, in the county of Chautauqua and State'of New York,.have invented certain new and useful Improvements in Perforated Sheet Metal, of which the follow' ing isa specification, reference being had to the accompanying drawings and to the reference characters marked thereon, which form a part of this specification.

This invention relates to perforated sheet metal, and more particularly to thin sheet l `the perforation forming an opening 2, the

metal in which a pluralityv of perforations are made in'relatively close proximity to each other.

In using thin sheet metal, as for'example, in cylinders of washing machines, it is very desirable to have all edges rounded and smooth so as to eliminate roughness, prevent tea-ring of garments which may come in contact with the edges, and prevent injury to the hands of the user.

Attempts have been made to obviate this trouble by dipping the perforated metal in a. liquid solution, such as molten tin, to cover the sharp and rough edges, or by binding the edges with strips of appropriate material. The dipping process is not satis' factory for the reason that in withdrawing the article from the tank, the liquid drops off and leaves sharp points; while the binding method is expensive and oftentimes impossible in certain arrangements of construction. t A.

By the present invention, I accomplish the desired result of perforating a Vsheet of thin metal., such as aluminunn, with a series of perforations relativelyv close together and" at thefsameV time,'rounding or beading the edge of the opening, thereby avoiding all sharpness and irregularities. I also so shape the sheet metal immediately adjacent to the beaded opening or perforation as to greatly strengthen the. same, thereby enabling me to use a large number of erforations without. roducing undue wea ness in the perforatedp sheet as a whole.

The invention consists in the improved article'herein illustrated and described, and the method of makin the same; all of which will be more fu y set forth in the appended claims.

In the drawing: Fig. 1 is a perspective view of a portion of a. sheet of thin metal, such as aluminum, to which my invention is particularly applicable.

Fig. 2 is a plan View showing the first operation of punching an aperture.

Fig. 3 is a sectional view, enlarged, taken in the plane of the line 3-3 of Fig. 2.

Fig. 4 is a plan view 'of the sheet of metal, showing the second operation.

Fig. 5 is a sectional view, enlarged, taken in the plane of the line 5 5 of Fig. 4.

By the use of any suitable punch, I perforate the sheet 1, as indicated in Fig. 2,

metal of the sheet 1 surrounding said opening being drawn or bent downwardly at the' 'the sheet l, as clearly shown in Fig. 5. In

other words, the thickness of the bead is greater than the thickness of the metal of the sheet 1, the whole having more of an embossed appearance than of a bent, drawn or punched effect. i

By sloping the metal from the ring 4 in- Wardly and downwardly toward the bead 5, I form a sort of truss-like structure which counterbalances the-weakness of the sheet due to the punching out step, and at the same time strengthens and braces the bead 5 to prevent distortion by strain or otherwise. This strengthening feature is further promoted by so shaping the dies as to locate the bead in its finished position at the end of the sloped portion, more on one side of the metal sheet than on the other. It will be seen by reference to Fig. 5, for example, that the ring 4 stands outwardly from the side or surface 6 of the sheet 1, while the bead 5 stands out lfrom the other surface 7 of said sheet.

I find in practice that this forms a very strong and durable construction. I have shown'but one perforation in'the sheet 1, but it will be understood that similar perforations may be made'in the sheet as closely together as the diameter of the rings 4 will permit.

1 claim as my invention:

l. The improved perforated sheet metal comprising a bead surrounding and defining the perforation and of a size greater than the thickness of the sheet metal, and an annular ring surrounding the beaded perforation and extending outwardly beyond one surface of the metal, the metal between the ring and the bead being indined.

2. The improved perforated sheet metal comprising a bead surrounding and delining the perforation and of a size greater than the thickness of the sheet metal, a portion of the bead being in a plane parallel'l to and beyond one surface of the sheet metal, and an annular trussA surrounding the bead.

In testimony that I claim the foregoing as my invention I afiix my si nature, in the 20 presence of two Witnesses, this 10th day of November. 1922.

GUNNARD A. OBERG.

Witnesses:

MAE LARsEN, FLORENCE HAMMOND. 

